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Author Topic: December 2010: Do You Have a 6 Bit LCD Monitor?  (Read 20260 times)
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« on: November 10, 2010, 12:45:20 PM »

December 2010: Do You Have a 6 Bit LCD Monitor?

 

Background

In need of a new LCD monitor recently, I went searching at the local Best Buy for a suitable replacement.  Even though I gave up on trying to get my recently acquired Mac computer to do anything useful and I eventually returned it, that Apple Cinema display was just gorgeous!  In fact, it spoiled me to the point that looking at my existing LCD PC monitor made me almost wish I had that Mac back on my desk.  So I went in search of a good LCD monitor for my Windows 7 system.  Surely I thought, technology has improved in the past ~3 years since I bought my last LCD monitor and I'd be able to just run to the local store and buy one equivalent to the Apple Cinema displays?  What I found were a host of new-tech LED backlit LCD displays that looked like they had potential by their specs, but after going to the store to review them, I was in for a big surprise.  I ended up losing almost 2 days of work trying to sort out the junk that is being sold now, researching different panel types such as TN versus IPS panels, and somewhere along the way, picking up on what appears to be a well guarded secret in the industry: that your typical LCD monitor that you find at your local brick and mortar stores can only display about 262,000 colors and not the 16.7 million that is being used by your 24 or 32 bit video board!  Read on if you want the details...

 

LED Backlit Monitors

The latest craze in LCD monitors are those that have LED backlighting.  Like the new LED TV's, they are basically the same LCD technology but their backlight uses LEDs instead of a fluorescent light source.  The advantage is lower cost, lower power consumption, and potentially smoother (more even) lighting across the screen.  What I found with the latest crop of LED monitors, however, is that because they are so light and thin (due to the LED lighting), the manufacturers seem to be using stands that are, simply put, a joke!  Even the high end models costing $300 from well known and respected brands use nothing more than a cheap plastic base that basically wobbles if you breathe on it!  In addition, instead of finding that the LED backlighting improved color like I expected, I found just the opposite.  I found the LED backlighting to be harsh and it caused strange color shifts that are unacceptable for photography. 

Whites have that harsh bluish glow (reminiscent of an LED flashlight) that make white shirts and other bright details look a bit pasty.  I tried two high end monitors from two different brands and have the same judgment about both of them: not suitable for photographic work.  Unlike LED TV's that seem to have better viewing angles, I found the viewing angles on the LED backlit LCD monitors to be almost as bad as old-tech LCD monitors.  The top of the monitor looks darker than the bottom and any shift of your head in front of the monitor causes color and contrast changes.  Knowing that it can be done right (the Apple Cinema displays don't have those problems), I ended up returning two of the LED LCD monitors and digging in to do a little deeper research.

 

TN LCD Panels

The first thing I found when researching why some monitors have such a contrast/angle issue is that almost all of your "standard" LCD monitors that you find in brick and mortar stores (including the LED backlit ones) use a panel technology called TN, short for Twisted Nematic.  While TN panels are cheaper and lighter than other technologies, they all suffer from the same contrast issues at different angles.  The TN technology is the reason that, if you fill your entire LCD monitor with a single shade of gray, the top of the monitor will look significantly darker than the bottom on a TN based panel.  The story only gets worse from there! 

What I found next is that in general, TN LCD panels can only display 6 bits per color channel.  Your images, your video card, and your display properties say you are running "True Color (32 bit)", yet you are only getting 18 bits of color that amounts to 262,000 colors, not the 16.7 million you thought you were getting!  Suddenly things started to make sense.  I've noticed for years that, when I display a gray gradient when doing graphics work (0,0,0 through 255,255,255), I could see clear and obvious banding in the grays.  It was noticeable: much more noticeable than it should be if I truly had 256 shades (8 bits) of gray.  I always blamed it on my monitor colorimeter that I use to profile my monitor, but now it made sense.  These "run of the mill" LCD displays that I've been using for years can only display 64 shades of any given color, not 256.  They try to hide that fact (some better than others) by dithering or high frequency color shifting, but it will be noticeable to most people.

I started to wonder how many people realize that, if they went into some local electronics store like Best Buy, Staples, Office Depot, etc. and walked out with an LCD monitor, chances are they just bought a monitor that can only display 262,000 colors.  Is this a "big secret" of the industry?  I wondered why, on this latest crop of LCD monitors, they offer a "sharpness" setting.  Why would such a thing even be necessary on a monitor where each pixel should be driven individually with sharpness being an attribute of the display software?  Why, when you crank up the sharpness, does text get color halos around it and when you turn it down, it gets blurry, and there seems to be no in between?  It all started to come together now.  Text is antialiased which means it isn't just black or white.  There are shades of gray... shades of gray that these LCD monitors based on the cheap TN technology can't display so it dithers the edges!  It just isn't true color (24 or 32 bit) and it affects everything from text to photos.  I wonder, like me, how many people fiddle with the sharpness on their LCD monitor only to find that one value (say 4) makes your text look blurry yet moving it to the next value (say 5) makes halos/artifacts appear around the text which makes it less readable?  That's the TN panel at work, trying to make the most of a limited color scheme!

 

IPS LCD Panels

I was finally able to find that the Apple Cinema displays are based on a better LCD technology called IPS, short for In-Plane Switching.  The details of the technology aren't as important as what it does for us consumers, particularly those of us who are into photography!  IPS panels are considered "professional grade" and they not only offer the full 16.7 million colors that 24 bit color (8 bits x 3 channels) provides, but they also offer smooth color response with almost no color shift based on viewing angle.  In addition, while the cheaper TN panels have a small color range (typically about 75% to 80% of the NTSC color space at best), the IPS panels can display more (and more vibrant) colors and typically cover a color space even larger than NTSC (about 110% or higher of NTSC color space).

While it is possible to spend $1000 or more on such LCD panels, I did manage to find several that were the same price or even cheaper than the $299 TN panels being sold at local stores!  The one I ended up with was a Viewsonic VP2365wb that I got for $269 but there are HP ZR series monitors in that price range as well, and a few other brands that get good reviews.  As soon as I connected the VP2365wb, I immediately realized what I had been missing.  Gradients were smooth again, text was razor sharp, and the color is simply magnificent.  I thought to myself, "I can definitely live with this monitor"!  This monitor was in the same league as the Apple Cinema Displays.  I felt like I had cracked the big secret of the el-cheapo monitors yet somehow I felt misled about what I had been buying previously.  Buyer beware!  I would recommend checking the panel technology of any monitor before you buy.  Of course, the manufacturers seem satisfied with keeping that a secret as well, since you'll rarely find the "panel technology" in specs.  What you can do is search the model number and "TN" to see if anyone is talking about that model on (for example) forums: they may mention that your model is a TN or IPS model.  My recommendation, at least for photography: stay away from TN based LCD monitors!.

 

S-IPS, H-IPS, MVA, PVA, and Other Confusing Acronyms

There are a lot of acronyms out there for different LCD display technologies but the most popular panel type for a good LCD display seems to be IPS at the current time.  Whether S-IPS, H-IPS, or some other incarnation, the "IPS" part is what is important.  I managed to find a decent list of IPS monitors and this is where I started my research.  If you are interested, you can check it out here

Here are some of the highlights of what you'll get if you buy an IPS monitor (versus the typical TN type LCD's sold in most stores):

  • Much better (more consistent) viewing at angles
  • Almost no contrast, color, or brightness shift from top to bottom of monitor
  • Much greater color range (gamut)
  • Smoother color with less banding: can display entire 16.7 million color range
  • Crisper text

And the only con I could find:

  • Slightly slower response time, but most reviewers don't notice, even for gaming
     

  Epilogue

I'm a software engineer by nature and I don't typically have time to follow all the latest trends in hardware, so maybe I'm a bit behind in "monitor tech" but I bet there are a lot of LCD monitor buyers out there who don't realize that their monitor can only display 6 bits (64 shades) of color per color channel, or about 262,000 colors.  The LCD monitors sold in almost all brick and mortar stores are based on TN panels which basically amount to old/cheap technology.  Even the newest LED backlit LCD monitors fall into this category of monitors that still have large contrast differences based on viewing angle and a limit of 262,000 colors.  This seemed like a "dark secret of the industry" that wasn't well known, so I wrote this article to help out.  If you've ever seen noticeable banding in gradients (like gray gradients) on your monitor, noticed that text isn't as sharp as it should be or text that has halos around it, or you notice that the image on your monitor gets very dark when you move your head down a bit, you've probably got a TN panel with these limited characteristics.  To be sure, you can do a web search and enter the model number of your monitor and the letters TN to see if you get hits telling you that your monitor is a TN panel.  If so, you're likely not getting the best image for photography.  You'll have to be the judge if whether or not this matters to you.  For me, I guess ignorance was bliss... until I saw what I was missing.

There is hope.  Get an IPS panel to solve all of the above problems!  This link will take you to a list where you can find professional grade IPS based LCD monitors and some are no more expensive than what you'll pay for the LCD monitors based on cheap TN technology that you'll see in a brick and mortar store!  While I've noticed clear banding artifacts when displaying (for example) a gray gradient on the non-IPS monitors, I rarely hear anyone complain that their monitor is only 6 bits per channel and can only display 262,000 of the 16.7 million colors provided by their graphics card.  Kinda makes me wonder, if you don't see that or at least you don't notice it, how can you possibly see the difference between a 24 bit (8 bit/channel) and a 48 bit (16 bits/channel) print?  Most people, even those who never realized that their existing LCD monitor could only display 6 bit color depth, still use their monitor as the benchmark and they try to match their prints to the monitor.  Their monitor is 6 bits yet they bought a printer that advertised it could print 16 bits just because, well, 16 sounded better than 8.  And there you have the full spectrum of how manufacturers sell products to consumers: from overrating (selling something that can't quite do what you assume it can) to overhyping (selling numbers you can't see or realize) at the other, and everything in between.  Food for thought!

 

Mike Chaney, author, Qimage, Profile Prism, FlashPipe, TT Dyno

« Last Edit: November 10, 2010, 12:51:33 PM by Mike Chaney » Logged
Jeff
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« Reply #1 on: November 11, 2010, 03:29:21 AM »

Thanks for that very interesting write up.

I have a Eizo S2110W, cost a lot of money, hope it conforms, I hardly dare to check Smiley

Jeff

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« Reply #2 on: November 11, 2010, 08:41:21 AM »

Thanks for the heads up as a new monitor is in my future.

I found the following link (go to the Head to Head Comparisons) very useful.
http://www.tftcentral.co.uk/reviews/viewsonic_vp2365wb.htm
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Terry-M
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« Reply #3 on: November 13, 2010, 05:35:21 AM »

An interesting article, thank you.
I bought an Eizo FlexScan W2242S last year so I've just checked out it's specification again, I think it's ok.!
It has a PVA panel, not as good as IPS in some respects but does give me 16.7 million colours  Cool Any viewing angle chromatic shift is not a problem with just me usually sitting in front of it but it ain't that bad anyway.  Cheesy
Jeff said,
Quote
I have a Eizo S2110W, cost a lot of money, hope it conforms, I hardly dare to check
I think yours is very similar.
Their ColorEdge monitors are probably IPS but very much more expensive.
Eizo stands are excellent, very sturdy, with full adjustment including height & rotation.
There is quite a good article on monitor choice here:
http://www.eizo.com/global/products/coloredge/CMS/02.html
and if you go back to page 1, there's a nice little explanation of Colour management too.
Terry
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« Reply #4 on: November 16, 2010, 08:20:36 PM »

The ViewSonic model that Mike mentions is representational of several, almost identically spec'd 22" and 23" LCD monitors available from different suppliers.  They all use an e-IPS display panel sourced from LG.  The most popular versions seem to be the Dell U2311h, The NEC EA231WMi, and the ViewSonic VP2365wb.  The monitors in this technology and price class are all normal gamut displays, meaning they effectively cover the sRGB color gamut, but no more.

E-IPS is the least expensive of the IPS panel technologies, but monitors employing e-IPS display panels are still far ahead of cheaper TN paneled displays in all the categories Mike describes in his article. Of course even the top end Eizos, NECs and Quatos still need to be hardware calibrated on a regular schedule.
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« Reply #5 on: November 17, 2010, 07:35:48 AM »

Since my post last week on this topic I purchased a Dell U2311H.

It is connected to my Dell Studio 17 laptop (Core i7 8GB RAM) as my primary monitor for image editing. It is kept company by 3 other monitors for a total of four (yeah, I know) - two on the laptop and two on a 5 year old desktop. They are literally side-by-side which happens to make for easy screen quality comparison. When it comes to the new Dell, it is visibly superior in terms of lack of banding in a typical grayscale test such as at http://www.drycreekphoto.com/Learn/Calibration/monitor_gradient.htm when I load this page on all four monitors and look at them side by side. All monitors are calibrated (regularly) using Eye-One.

For others contemplating or using multiple monitors and/or multiple PCs, I've found the following more than a little useful.
1. Ultramon - a multi-monitor utility which I find more useful than adding a 2nd monitor and allowing it to be just an extension of the 1st monitor's screen
2. Synergy - which from Synergy's website "....lets you easily share a single mouse and keyboard between multiple computers with different operating systems, without special hardware. All you need is a LAN connection. It's intended for users with multiple computers, where each system uses its own display." This program is only a bit removed from magic when it comes to working with multiple computers (how about being able to "cut" on one and "paste" it on the other as an example). With a single left-to-right roll of the mouse I can move from the left end of the laptop, across the new Dell, onto and across the desktop's "primary" monitor and finally to the right side of the desktop's "text-only" monitor. The keyboard works on which ever monitor the mouse is over at that instant.

I have no affiliation with the purveyors of any of the aforementioned products - just a satisfied customer.
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« Reply #6 on: November 22, 2010, 11:22:28 AM »

The ViewSonic model that Mike mentions is representational of several, almost identically spec'd 22" and 23" LCD monitors available from different suppliers.  They all use an e-IPS display panel sourced from LG.  The most popular versions seem to be the Dell U2311h, The NEC EA231WMi, and the ViewSonic VP2365wb.  The monitors in this technology and price class are all normal gamut displays, meaning they effectively cover the sRGB color gamut, but no more.

E-IPS is the least expensive of the IPS panel technologies, but monitors employing e-IPS display panels are still far ahead of cheaper TN paneled displays in all the categories Mike describes in his article. Of course even the top end Eizos, NECs and Quatos still need to be hardware calibrated on a regular schedule.

The VP2365wb actually covers 82% of the NTSC gamut which is a bit larger than sRGB which covers about 72%.  The gamut of the WP2365wb is actually somewhere between sRGB and Adobe RGB.

Mike
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« Reply #7 on: November 22, 2010, 11:59:46 AM »

The VP2365wb actually covers 82% of the NTSC gamut which is a bit larger than sRGB which covers about 72%.  The gamut of the WP2365wb is actually somewhere between sRGB and Adobe RGB.

Mike

Same as the other two monitors I mentioned.  Dell states the gamut coverage of the U2311h as 82% NTSC (100% sRGB coverage).  Bottom line is, these are all great monitors for a modest cost.
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« Reply #8 on: February 15, 2011, 05:01:57 PM »

Great article, Mike.  I've bookmarked it for future reference when it's time to upgrade my monitor.  Thanks.
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